git-instaweb: unconditionally assume that gitweb is mod_perl capable

git-instaweb: unconditionally assume that gitweb is mod_perl capable

Remove a check for whether mod_perl is a supported mode of gitweb.cgi
added in a51d37c1df6 (Add git-instaweb, instantly browse the working
repo with gitweb, 2006-07-01).

The reason for the check was to support users who had a newer version
of git and an older version of gitweb, it was then subsequently
adjusted for changes in the script in f0e588dffc1 (git-instaweb: fix
mod_perl detection for apache2, 2009-08-08).

It's a fair bet that nobody's running a git from 2021 and gitweb from
pre-2007 anymore, so we can unconditionally assume that this will be
supported by gitweb.cgi.

This allows a subsequent commit to remove the sane_grep() wrapper,
this change is split up from that since this is the only case where
the "grep" invocation could be removed entirely.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>